I do have a side panel, although it isn't a clear one. However, I was planning to get a new case shortly after I got this upgrade, with a better side panel, but I am still searching for a good one of around €50-€70.
Not a huge one. The X generally has a higher XFR rate, but you can manually overclock to the same speed. TDP doesn't play an enormous factor for overclocking between the two. I'd just get the cheaper on personally.